External fixator system

ABSTRACT

An external fixation frame for correcting a bone deformity includes a first fixation ring and a second fixation ring. A posterior adjustable length strut couples a posterior portion of the first fixation ring to a posterior portion of the second fixation ring and has universal joint. Medial and lateral adjustable length struts couples medial and lateral portions of the first fixation ring to medial and lateral portions of the second fixation ring respectively, each of the medial and lateral adjustable length struts including a constrained hinge joint. The fixation frame also includes a half ring hingedly coupled to the second fixation ring, and an anterior adjustable length strut coupling an anterior portion of the first fixation ring to the half ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/564,675, filed Dec. 9, 2014, which is a continuation of U.S.patent application Ser. No. 13/792,634, filed Mar. 11, 2013, now U.S.Pat. No. 8,945,128, which is a continuation-in-part of U.S. patentapplication Ser. No. 13/206,058, filed Aug. 9, 2011, now U.S. Pat. No.8,834,467, which application claims priority to European Application No.10 172 523.2, filed Aug. 11, 2010, and European Application No. 11 176512.9, filed Aug. 4, 2011. The disclosures of each of the abovereferenced applications are hereby incorporated by reference herein intheir entireties.

FIELD OF THE INVENTION

The present disclosure relates to an external fixation frame forcorrecting a bone deformity. More particularly, the present disclosurerelates to an external fixation frame having an arch or half-ringconnected to a bottom fixation ring of the external fixation frame.

BACKGROUND OF THE INVENTION

Many different types of bone deformities can be corrected using externalfixation systems to perform the distraction osteogenesis process. Forexample, an Ilizarov device or similar external fixation system may beused. Such systems generally use rings also designated as fixationplates connected by threaded rods or struts with nuts for manipulation,angulation, and translation of the length discrepancies of bones. Thenuts that are used to adjust the length of the struts are generallymanually adjusted by a surgeon or by the patient with a wrench or byhand to change the positions of the rings and/or percutaneous fixationcomponents.

As the position adjustments of the components are made where the nutsare secured, it can be difficult for the patient, for example, to makethe required daily adjustments with consideration of maintaining stablefixation. Other devices use different techniques to adjust the effectivelength of the struts or rods but all must be adjusted somewhere betweenthe ends thereof. The devices generally offer limited access for thepatient. Because the adjustments are often a daily task for the patient,easier access to the frame adjustment points would be a significantadvantage.

Fixation systems, especially foot fixation systems, have many areas ofneeded improvement. For example, existing foot fixation products on themarket are static and do not allow for adjustment and pivoting. Certainfoot fixation systems include a solid and stationary half-ring assembledto the foot ring. This lack of flexibility and motion restricts themotion of the foot and ankle and the external fixation frame duringdeformity correction, making the process more difficult for thephysician and the patient and potentially preventing an optimal clinicaloutcome.

To allow for deformity correction of the foot and ankle, an adjustableand pivoting component that can be assembled onto the distal portion ofa foot ring of an external fixation frame is needed.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, an external fixation frame for correcting a bonedeformity includes a first and second fixation ring. A posterioradjustable length strut couples a posterior portion of the firstfixation ring to a posterior portion of the second fixation ring, theposterior adjustable length strut including a universal joint at an endthereof. Medial and lateral adjustable length struts couple medial andlateral portions of the first fixation ring to medial and lateralportions of the second fixation ring, respectively. The medial andlateral adjustable length struts include a constrained hinge joint atends thereof. A half ring is hingedly coupled to the second fixationring and an anterior adjustable length strut couples an anterior portionof the first fixation ring to the half ring.

The half ring may include a lateral end potion, a medial end portion,and an arcuate body portion connecting the lateral end portion to themedial end portion. The medial end portion of the half ring includes afirst constrained hinge joint and the lateral end portion of the halfring includes a second constrained hinge joint. The second fixation ringmay be U-shaped and include a medial anterior projection, a lateralanterior projection, and a rounded posterior section connecting themedial anterior projection to the lateral anterior projection. The firstconstrained hinge joint may couple the medial end portion of the halfring to the medial anterior projection of the second fixation ring andthe second constrained hinge joint may couple the lateral end portion ofthe half ring to the lateral anterior projection of the second fixationring.

The anterior adjustable length strut may include a distal constrainedhinge joint and a proximal universal hinge joint. The distal constrainedhinge joint of the anterior adjustable length strut may be coupled tothe arcuate body portion of the half ring and the proximal universalhinge joint of the anterior adjustable length strut may be coupled tothe anterior portion of the first fixation ring. The medial adjustablelength strut and lateral adjustable length strut may each include anaperture proximal of the constrained hinge joint, each aperture beingconfigured to accept a wire fastener therethrough. The half ring mayinclude an aperture with a diameter and the anterior adjustable lengthstrut may include a connecting element at a distal end thereof. Theconnecting element may include internal threading on the distal end ofthe strut and an externally threaded bolt, a portion of the bolt havinga diameter greater than the diameter of the half ring aperture.

The external fixation frame may also include a rocker member coupled toa bottom surface of the second fixation ring. The rocker member mayinclude a curved body portion with at least one connecting elementprojecting proximally from the curved body portion and configured tomate with an aperture in the second fixation ring. The connectingelement may include a main body portion extending through an aperture inthe curved body portion of the rocker member and a distal flange. Thedistal flange may extend distally of the main portion and be configuredto contact a corresponding shoulder portion of the aperture in thecurved body portion. The rocker member may further include aground-contacting rounded distal portion coupled to a distal portion ofthe curved body portion of the rocker member, the ground-contactingrounded distal portion having a textured ground-contacting surface.

In another embodiment, an external fixation frame for correcting a bonedeformity may include a first and second fixation ring. The secondfixation ring may have a first free end, a second free end, and anarcuate portion connecting the first free end to the second free end. Atleast four struts couple the first fixation ring to the second fixationring. At least one bone fastener has a first end operably coupled to thefirst free end of the second fixation ring and a second end operablycoupled to the second free end of the second fixation ring. A half ringhas a first free end, a second free end, and an arcuate portionconnecting the first free end to the second free end. The first free endof the half ring is coupled to the first free end of the second fixationring and the second free end of the half ring is coupled to the secondfree end of the second fixation ring. The bone fastener may be a K-wire.The external fixation frame may also include a first compression modulecoupled to the first free end of the second fixation ring and a secondcompression module coupled to the second free end of the second fixationring. The first end of the bone fastener may be coupled to the firstcompression module and the second end of the bone fastener may becoupled to the second compression module.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the followingwith reference to the drawings, which are for the purpose ofillustrating the present preferred embodiments of the invention and notfor the purpose of limiting the same.

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIGS. 1A-C show side views of different strut configurations of anexternal fixator system of the present invention with first and secondplates coupled to a tibia and a foot of a patient respectively;

FIG. 2 shows an embodiment of an actuation unit of the present inventionused in the external fixator system of FIGS. 1A-C;

FIG. 3 shows a cross-sectional view of the actuation unit of FIG. 2;

FIG. 4 shows a perspective partial cross-sectional view of the actuationunit of FIG. 3;

FIG. 5 shows the actuation unit of the previous figures in connectionwith an adjustable length strut to be used to connect two rings of theexternal fixator with each other; and

FIG. 6 shows a detailed view of FIG. 5.

FIG. 7 shows a perspective view of an external fixation frame accordingto another embodiment of the invention.

FIG. 8A shows a front plan view of a half-ring of the external fixationframe shown in FIG. 7.

FIG. 8B shows a perspective view of the half-ring of FIG. 8A.

FIG. 8C shows a partial cross-sectional view of the half-ring of FIG.8A.

FIGS. 9A-B show top plan views of a bottom fixation ring of the externalfixation frame shown in FIG. 7.

FIG. 10A shows a perspective view of a rocker shoe of the externalfixation frame shown in FIG. 7.

FIGS. 10B-D shows various plan views of the rocker shoe of FIG. 10A.

FIG. 10E shows an exploded view of the components of the rocker shoe ofFIG. 10A.

FIG. 10F shows a perspective view of the rocker shoe of FIG. 10E.

FIG. 11A shows a perspective view of a universal hinge strut of theexternal fixation frame shown in FIG. 7.

FIGS. 11B-D show various plan views of the universal hinge strut shownin FIG. 11A.

FIG. 12A shows a perspective view of a constrained hinge strut of theexternal fixation frame shown in FIG. 7.

FIGS. 12B-D show various plan views of the constrained hinge strut shownin FIG. 12A.

FIGS. 13A-D show various views of a constrained hinge joint of theconstrained hinge strut shown in FIGS. 12A-D.

FIG. 14A shows a perspective view of one embodiment of a half-ring strutof the external fixation frame shown in FIG. 7.

FIG. 14B shows a perspective view of another embodiment of a half-ringstrut of the external fixation frame shown in FIG. 7.

FIGS. 14C-E show various plan views of the half-ring strut shown in FIG.14B.

FIG. 14F shows an enlarged perspective partial view of a connectingelement of the half-ring strut shown in FIGS. 14B-E.

FIG. 15 is a perspective view of an alternate embodiment of an externalfixator system.

FIG. 16 is a perspective view of the bottom fixation ring andcompression modules of the external fixator system of FIG. 15.

DETAILED DESCRIPTION

As used herein, the term “proximal” means a direction closer to theheart of a patient and the term “distal” means a direction farther awayfrom the heart of a patient. The term “anterior” means towards the frontpart of the body or the face and the term “posterior” means towards theback of the body. The term “medial” means toward the midline of the bodyand the term “lateral” means away from the midline of the body.

Referring to FIGS. 1-6, there is shown an embodiment of an externalfixator system of the present invention. As shown in those figures, theexternal fixator system includes first and second fixation plates 1, 2coupled to first and second bone segments L, F respectively, a pluralityof adjustable length struts 3, at least one actuation unit 4, and aplurality of clamping units 4′.

FIGS. 1A-E show an exemplary embodiment of an external fixator system.The external fixator system comprises at least two fixation plates 1, 2which are arranged at a distance to each other and at least oneadjustable length strut 3 which is in connection with the fixationplates 1, 2. Such struts are shown in U.S. Publications 200910198234 and200910198235 the disclosures of which are incorporated herein byreference in their entirety. Fixation plates 1, 2 serve as bearingelements for pins which are in connection with bony structure such asfirst and second bone segments L, F, for example. The orientation aswell as the distance between two fixation plates 1, 2 thereby define theorientation and distance between fractured elements of the bonystructure. Each of the fixation plates 1, 2 comprises a front surface 12which extends over the largest dimension of the plate 1, 2.

In the present embodiment there is an upper fixation plate 1 inconnection with the lower leg L and a lower fixation plate 2 inconnection with the foot F. The lower fixation plate 2 comprises also arolling structure 20 to enable a user to walk around.

Adjustable length struts 3 each include a length adjusting mechanism 32having a threaded strut 33 and a non-rotating strut 34 having aninternal thread along at least a portion of a length thereof in whichthe threaded strut 33 engages. Struts 3 include a first end region 30and a second end region 31 in which the struts 3 are coupled to therespective fixation plates. In the present embodiment the struts 3 areconnected to the upper fixation plate 1 by means of an actuation unit 4and to the lower fixation plate 2 by means of a clamping element 4′. Itis also possible to use an actuation unit 4 to connect the strut 3 tothe upper fixation plate 1 as well as to the lower fixation plate 2. Theactuation unit 4 is preferably provided to actuate the length-adjustingstrut in order to adjust its length.

The actuation unit 4 is preferably in a fixed connection with fixationplates 1, 2 as shown in FIGS. 1A-E. The term fixed connection is to beunderstood as being a connection which prevents unintentional relativemotion between the actuation unit 4 and fixation plates 1, 2. Inparticular, a rotational motion is preferably prevented. Preferably,fixation plates 1, 2 comprise a plurality of openings 10 in which suchactuation units 4 can be arranged and such that the fixed connection canbe established. The fixed connection has the advantage such that thedevice can be adjusted easily without the aid of several tools.

FIG. 2 shows the actuation unit 4 in a perspective view and FIGS. 3 and4 show sectional views. The actuation unit 4 comprises an outer sleeve 5in which an actuation element 6 is arranged. The actuation unit 4 is inconnection with the fixation plate 1, 2 by means of the outer sleeve 5.Outer sleeve 5 is shown having a partly round configuration but may haveother configurations such as rectangular, spherical, square and thelike.

The outer sleeve 5 extends along a middle axis M as shown in FIG. 3 andcomprises a through opening 50, a clamping section 51 and a bearingsection 52. The clamping section 51 includes a threaded section 53 and ashaft section 54. The threaded section is in contact with a nut 56 whichis used to secure the outer sleeve 5 to the fixation plate 1, 2. On theouter side a flange 55 divides the clamping section 51 from the bearingsection 52. The bearing section 52 has mainly two purposes, namely tobear the actuation element and to provide a bearing of the outer sleeve5 in the opening 10. Hence the inner side provided by said throughopening 50 serves to provide a bearing for an actuation element 6 ofactuation unit 4. The outer side of the bearing section 52 serves mainlyto provide a bearing for the outer sleeve 5 within said opening 10 inthe ring 1 as explained below with regard to FIG. 3 in more detail. Theouter side of the bearing section 52 has in the present embodiment arectangular cross section with rounded edges 57 and flat sidewalls 58.Edges 57 and sidewalls 58 extend parallel to the middle axis M. The partwhich is located in vicinity of flange 55, however, is preferably alsoin connection with the opening in the fixation plate 1, 2.

In FIG. 3, one embodiment of an opening 10 in the fixation plate 1, 2 isschematically shown. The opening 10 comprises a shoulder 11 whichsubdivides the opening 10. The opening 10 comprises a first section 13and a second section 14. The shoulder 11 is located between the firstsection 13 and the second section 14. The first section 13 of theopening 10 has therefore a complementary or corresponding shape as theshaft section 54. In the present embodiment shaft section 54 as well asfirst section 13 have circular cross-sections and the second section 14as well as the bearing section 52 have a rectangular cross-section.

When the outer sleeve 5 is inserted into the opening 10 the shoulder 11is preferably in contact with flange 55. The shaft section 54 of theouter sleeve 5 extends through the first section 13 of the opening 10and the bearing section 52 extends into the section 14. The outer sleeve5 is fixed to the fixation plate 1, 2 by means of nut 56 which retractsthe outer sleeve 55 relative to fixation plate 1, 2 such that flange 55comes in contact with the shoulder 11.

From FIG. 2 it becomes evident that the cross-section of the outersurface of the bearing section 52 which is in contact with the opening10 is provided such that rotation of outer sleeve 5 relative to thefixation plate 1, 2 is prevented. For that reason the opening 10 has acomplementary shape. In the present embodiment, the outer sleeve 5 haspartly a rectangular cross-section with rounded edges. Here therectangular cross-section is mainly provided by the outer side of thebearing section 52 or the outer surfaces of the bearing section 52,respectively.

The actuation element 6 of actuation unit 4 preferably extends along themiddle axis M and comprises mainly a shaft section 60 which extendsthrough the opening 50 of the outer sleeve and a connection section 61which is in connection with strut 3. The actuation element 6 can beactuated, i.e. rotated, by means of a tool 67 shown in FIG. 5, whichpreferably engages in a socket 66 of the actuation element 6. Socket 66is thereby arranged such that the tool can be introduced in a directionwhich is more or less in line with the axis of the strut or in adirection perpendicular to the fixation plate 1, 2 in particular tosurface 12. The orientation of the socket 66 has thereby the advantagethat easy access is provided from the top of the fixation system andthat the length of the struts 3 can be adjusted easily by any user ofthe system.

The actuation element 6 is borne by means of a ball bearing 9 in theouter sleeve 5. In the present embodiment, the ball bearing 9 isprovided by means of the shaft section 61 and the bearing section 52. Aseparate ball bearing is also possible, but a ball bearing which isprovided according to the embodiment of FIG. 3 is preferably compact interms of size.

As shown in FIG. 3, the bearing section 52 and the shaft section 61preferably comprise respective grooves 90, 91 in which a plurality ofballs 92 are arranged. Groove 90 extends into the surface of the opening50 and encompasses the whole opening 50, whereas groove 91 is arrangedin the shaft 61 of the actuation element 6. The grooves 90, 91 provide achannel in which the balls 92 are arranged. Balls 92 may be introducedinto the channel via an opening 93 in the shaft section 61 which iscovered by means of a cover 94.

Between the outer sleeve 5 and the actuation element 6 there is arrangeda feedback unit 7 as shown in FIGS. 3 and 4. In the present embodiment,the feedback unit 7 is provided by means of a spring -loaded ball 70 andcorresponding chambers 71. The spring-loaded ball 70 is arranged in anopening 72 in the actuation element 6. Between the ground of the opening72 and the spring-loaded ball 70 there is arranged a spring 73 whichprovides a force that pushes the ball 70 into a respective chamber 71.The chambers 71 are arranged in the surface of the through opening 50 inthe outer sleeve 5. Upon rotation of the actuation element 6 relative tothe outer sleeve 5, the spring-loaded ball 70 is pushed against thespring force by means of the transition portion 74 between twoneighboring chambers 71. As soon as the next chamber 71 is in line withthe spring axis, the spring-loaded ball 70 will be moved into therespective chamber 71. This mechanism results in a clicking noise whichprovides the user with a respective audible feedback about the amount ofactuation that is being made.

There are a plurality of chambers 71 arranged which are preferablydistributed evenly around the perimeter of the through opening 50 of theouter sleeve 5. In the present embodiment, eight chambers 71 arearranged such that each chamber is located approximately 45° from aneighboring chamber, but it is also possible to arrange more or lessthan eight chambers. The number of chambers preferably depends on theapplication. Preferably, each time the actuation element is rotated suchthat the spring-loaded ball moves from one chamber 71 and into aneighboring chamber 71, adjustable length strut is lengthened 1 mm. Eachtime the actuation element is rotated such that the spring-loaded ballmoves from one chamber 71 and into a neighboring chamber 71, adjustablelength strut may be lengthened between 0.1 mm to 1 mm.

It is important for the adjustable length strut to not be lengthened soeasily or inadvertently such that accidental injury may be caused.Osteogenesis generally occurs over a considerable length of time andlengthening and/or angulation adjustment between adjacent bone fragmentsshould only be done in a prescribed manner. Therefore, chambers 71 arepreferably deep enough to securedly house at least a portion of thespring loaded ball 70 and a spring constant k of the spring issufficient enough to force the ball against side walls in the respectivechambers such that preferably only intended actuation of the actuationunit causes the actuation unit to actuate.

With regard to the embodiment as shown in FIGS. 3 and 4, opening 72 canalso be arranged in the outer sleeve 5 and that the chambers 71 can alsobe arranged in the actuation element 6. With such a configuration a sameor similar result can preferably be achieved.

The strut 3 with its end region is in a fixed connection with theactuation element 6. In the present embodiment, there is a Cardan(universal) joint 62 arranged between the strut 3 and the actuationelement 6 in order to compensate angular differences between the strut 3and the actuation element 6. Furthermore the actuation element 6comprises an opening 63 in which the strut 3 extends as shown in FIG. 6.Preferably the strut 3 is in connection with the opening 63 by means ofa thread, a press fit or any other suitable connection method whichprevents a relative movement between the strut 3 and the actuationelement 6. In case a thread is used, it is advantageous to secure thethread by means of a pin 64 which extends through the opening 63 and thestrut 3. For that reason a pin opening 65 is arranged in the region ofthe opening 63. The use of a Cardan joint 62 has the advantage thatadjustments can be made in advantageous manner, namely in a preferablyprecise and smooth manner.

Upon rotation of the actuation element 6, the strut will also be rotatedand its length will be adjusted according to the degree of rotation. Thefeedback unit 7 then provides the user with an acoustic as well as witha haptic feedback due to its mechanical structure as outlined above.

Upon rotation of the actuation element 6, the strut will also be rotatedand its length will be adjusted according to the degree of rotation. Thefeedback unit 7 then provides the user with an acoustic as well as witha haptic feedback due to its mechanical structure as outlined above.

The arrangement of the feedback unit 7 as mentioned herein has theadvantage that in terms of dimension a very compact structure can beachieved. Thereby the overall weight can be significantly reduced and itis preferably more convenient for the patient to use such a structure.

As shown in FIG. 2, markings 67 showing the direction of rotation arearranged on an outer face of actuation unit 4 in order to allow the userto know in which direction actuation unit 4 is being actuated. In thisregion it is also possible to arrange a scale on which the user canvisually recognize the amount of rotation, whereby a visual feedback canbe provided.

FIGS. 5 and 6 show the strut 3 in connection with actuation unit 4 byway of its first end region 31 and with the clamping element 4′ via itssecond end region 32. The clamping element 4′ clamps the strut 3 infixed manner to the fixation plate 1, 2 which is not shown here. Theactuation unit 4 is also in a fixed connection with the respectivefixation plate, but the actuation element 6 which is arranged within theactuation unit 4 is rotatable relative to the actuation unit 4. Arotation of the actuation element 6 preferably results in a rotation ofthe threaded strut 33 and in connection with the non-rotating strutsection 34 such that the length of the strut 3 will be adjusted.

FIG. 7 illustrates a perspective view an embodiment of an externalfixator similar to that illustrated in FIGS. 1A-C. Similar parts aregenerally identified by a number 100 greater than the corresponding partidentified in FIGS. 1A-C. FIG. 7 particularly illustrates a half-ring113 hingedly coupled to the bottom fixation ring 102 and coupled to thetop fixation ring 101 via half-ring strut 103 c. Although the termhalf-ring is used, it should be understood that the half-ring is notlimited to being half of a circular ring, but may take other shapes,preferably generally arcuate shapes. The top fixation ring 101 isfurther connected to the bottom fixation ring 102 with constrained hingestruts 103 b and a universal hinge strut 103 a.

As illustrated in FIG. 7, the half-ring 113 is coupled to the anteriorpart of the bottom fixation ring 102. Among other benefits, thehalf-ring 113 closes the open bottom fixation ring 102 such that theopen bottom fixation ring does not deflect, or only minimally deflects,when fixation features, such as Kirschner wires (“K-wires”) 114 aretensioned. Without half-ring 113, tensioning a member fixed at oppositeends of the open bottom fixation ring 102, such as a K-wire 114, maytend to cause the open portions of bottom fixation ring to deflectcloser together. This deflection is limited by the rigid connection ofthe half-ring 113 to the bottom fixation ring 102.

The half-ring 113 is best illustrated in FIGS. 8A-C. The half-ring 113may include a generally arcuate main portion 1300 similar to a portionof one of the fixation rings 101, 102. Similar to the fixation rings101, 102, the half-ring 113 may include a number of openings 1310 tofacilitate other members, such as half-ring strut 103 c, to be attachedto the half-ring.

The half-ring 113 may also include hinges 1320 at the ends of the mainportion 1300. The hinges 1320 may include a first hinge portion 1322 anda second hinge portion 1324. The first hinge portion 1322 may be coupledto the half-ring 113, for example by an adhesive, or may alternately beintegral with the half-ring. As illustrated in FIG. 8C, the first hingeportion 1322 may include a pronged connecting portion 1323 that mateswith recesses in an end of the main portion 1300 of the half-ring 113.The fit may be a compression fit or a snap fit, or may otherwise befixed, for example by an adhesive.

The first hinge portion 1322 may also include a textured surface and anaperture to accept a fastener. The aperture preferably is unthreaded.The fastener may be, for example, a screw 1326 with a first portion ofthe screw shaft unthreaded and a second portion of the screw shaftthreaded. The second hinge portion 1324 may be of a generally similarstructure to the first hinge portion 1322, having a textured surface andan aperture to accept a fastener. Preferably, the aperture is internallythreaded.

The second hinge portion 1324 may also include a connecting portion1325. The connecting portion 1325 may, for example, be cylindrical andconfigured to pass through an aperture 10 in the bottom fixation ring 2.The connecting portion 1325 may also be threaded to mate with a lockingnut or other fastener to secure the second hinge portion 1324 in a fixedrelation to the bottom fixation ring 2.

The screw 1326 may be inserted through the unthreaded aperture in thefirst hinge portion. Preferably the unthreaded aperture is large enoughthat the shaft of the screw 1326 can move freely through the aperture.The threaded portion of the screw 1326 is then inserted through thethreaded aperture in the second hinge portion 1324. The threadedaperture is preferably dimensioned such that the screw 1326 must berotated to pass through the threaded aperture. As the screw 1326 isrotated, the second hinge portion 1324 is drawn toward the first hingeportion 1322. When fully inserted, the unthreaded portion of the screw1326 generally is located at the unthreaded aperture of the first hingeportion 1322 and the threaded portion of the screw is engaged with thethreaded aperture of the second hinge portion 1324. In this position,the first hinge portion 1322 and second hinge portion 1324 arefrictionally engaged such that rotation of the first hinge portionrelative to the second hinge portion about the screw 1326 is resisted.In the embodiment in which one or both of the hinge portions 1322, 1324include textured surfaces, such as ridges, the engagement of thetextured surfaces may provide additional resistance against rotation. Anut may also be threaded onto any portion of the screw 1326 that extendsbeyond the aperture in the second hinge portion 1324 to help preventunintentional rotation of the screw 1326 when in the fully threaded,locked position.

The bottom fixation ring 102 is illustrated in FIGS. 9A-B. The bottomfixation ring 102, in the particular embodiment shown, is generally “U”shaped with a posterior base 1020 and anterior projections 1022. Thebottom fixation ring 102 may include a number of apertures or openings1024 extending along the length of the bottom fixation ring. Althoughone particular pattern of openings 1024 is illustrated in FIG. 9, thenumber and placement of the openings 1024 is largely a matter of designchoice. The openings 1024 may be used to connect components to thebottom fixation ring 102, such as a variety of struts and compressionmodules, as is explained in further detail below. Preferably, enoughopenings 1024 exist such that a surgeon or other user has a variety ofchoices in the placement of such components.

Rolling structure, or rocker 120, is illustrated in FIGS. 10A-F.Generally, rocker 120 has an elongate main body 1200 and an elongateground-contacting rounded portion 1201. The ground-contacting roundedportion 1201 may include treads or other surface texture to increasefriction with the ground. The ground-contacting rounded portion 1201 maybe integral with the main body 1200, or may be otherwise coupled to themain body, for example by adhesive. The main body and ground-contactingrounded portion may include openings 1202 and 1203, respectively.

The main body 1200 of the rocker 120 may include one or more connectingpins 1205 (three connecting pins illustrated in FIGS. 10A and 10E-F, twoconnecting pins illustrated in FIGS. 10B-D). As best illustrated in FIG.10B, the connecting pins 1205 may be generally cylindrical anddimensioned to securedly fit within an opening 1202 of the main body1200. The bottom of the connecting pins 1205 may include a flange 1206larger than the diameter of the opening 1202, such that the connectingpins 1205 cannot be pulled proximally through the rocker 120. A recess1207 may be formed on a distal end of the main body 1200 where eachconnecting pin 1205 is located. The recess 1207 is formed such that theflange 1206 of the connecting pin 1205 is situated distal to the mainbody 1200 and proximal to the ground-contacting rounded portion 1201 ofthe rocker 120. The distal end of the connecting pins 1205 may bethreaded and configured to fit through openings 1024 of the bottomfixation ring 102 to secure the rocker 120 to the bottom fixation ring.The distal end of the connecting pins 1205 may be threaded to accept alocking nut 1208 to lock the rocker 120 to the bottom fixation ring 102.

Although only one rocker 120 is illustrated in FIGS. 10A-F, it should beunderstood that two rockers would be used with the bottom fixation ring102 to provide stable contact with the ground. Also, the rockers 120 maybe identical, or may be similarly or symmetrically shaped. For example,as seen in FIG. 10D, the rocker 120 may include contours, which contoursmay be mirrored in a second rocker that is used with the bottom fixationring.

As discussed above, multiple struts may be used to connect components ofthe fixation system and to allow for various types of movement andpositioning between the components. In the illustrated embodiment, atleast three different types of struts are used, including universalhinge struts 103 a, constrained hinge struts 103 b and half-ring struts103 c.

Now referring to FIGS. 11A-D, universal hinge strut 103 a may be similarto the adjustable length strut 3 described above. In one embodiment,universal hinge strut 103 a includes a length adjusting mechanism havinga threaded strut 133 a and a non-rotating strut 134 a having an internalthread along at least a portion of a length thereof in which thethreaded strut 133 a engages. Universal hinge struts 103 a may beconnected to the upper fixation plate 101 by means of an actuation unit104 a and to the lower fixation plate 102 by means of a connectingelement 104 a′. It is also possible to use an actuation unit 104 a toconnect the universal hinge strut 103 a to the upper fixation plate 101as well as to the lower fixation plate 102. The actuation unit 104 a ispreferably provided to actuate the length-adjusting strut in order toadjust its length.

The actuation unit 104 a may be substantially similar to the actuationunit 4 described above, including a ball and spring mechanism to provideauditory and/or tactile feedback. In the illustrated embodiment,universal hinge strut 103 a includes a universal joint 162 a near theconnecting element 104 a′. This is in contrast to the strut 3 describedabove, in which the universal joint 62 is positioned closer to theactuation element 4. The internal mechanisms described with relation tostrut 3, however, generally apply with equal force to the universalhinge strut 103 a. The universal hinge strut 103 a may also include aquick-release mechanism 135 a. Generally, the quick-release mechanism135 a has a locked position and an unlocked position. In the lockedposition, the threaded strut 133 a can move into or out of thenon-rotating strut 134 a only by rotation of the threaded strut into thenon-rotating strut. In the unlocked position, the threaded strut 133 amay be moved into or out of the non-rotating strut 134 a withoutrotation of the threaded strut, such that a user may quickly move thethreaded strut into the non-rotating strut. This mechanism is more fullydescribed in U.S. patent application Ser. No. 13/592,832, titled “BoneTransport External Fixation Frame.”

Now referring to FIGS. 12A-D, constrained hinge struts 103 b are nearlyidentical to universal hinge struts 103 a, with a constrained hingejoint 168 rather than a universal hinge joint 162. The constrained hingejoints 168 allow for constrained rotation using a similar or identicalmechanism as hinges 1320 of the half-ring 113. Similar to the universalhinge strut 103 a, constrained hinge strut 103 b includes a lengthadjusting mechanism having a threaded strut 133 b and a non-rotatingstrut 134 b having an internal thread along at least a portion of alength thereof in which the threaded strut 133 b engages. Constrainedhinge struts 103 b may be connected to the upper fixation plate 101 bymeans of an actuation unit 104 b and to the lower fixation plate 102 bymeans of a connecting element 104 b′. It is also possible to use anactuation unit 104 b to connect the constrained hinge strut 103 b to theupper fixation plate 101 as well as to the lower fixation plate 102. Theactuation unit 104 b is preferably provided to actuate thelength-adjusting strut in order to adjust its length.

The actuation unit 104 b may be substantially similar to the actuationunit 4 described above, including a ball and spring mechanism to provideauditory and/or tactile feedback. In the illustrated embodiment,constrained hinge strut 103 b includes a constrained joint 168 b nearthe connecting element 104 b′. The constrained hinge strut 103 b mayalso include a quick-release mechanism 135 b.

Constrained hinge joint 168 is shown in more detail in FIGS. 13A-D. Theconstrained hinge joint 168 may include a first hinge portion 1422 and asecond hinge portion 1424. The first hinge portion 1422 may be coupledto non-rotating strut 134 b. The second hinge portion 1424 may becoupled to the connecting portion 104 b′.

The first hinge portion 1422 may also include a textured surface and anaperture to accept a fastener. The aperture preferably is unthreaded.The fastener may be, for example, a screw 1426 with a first portion ofthe screw shaft unthreaded and a second portion of the screw shaftthreaded. The second hinge portion 1424 may be of a generally similarstructure to the first hinge portion 1422, having a textured surface andan aperture to accept a fastener. Preferably, the aperture is internallythreaded.

The screw 1426 may be inserted through the unthreaded aperture in thefirst hinge portion. Preferably the unthreaded aperture is large enoughthat the shaft of the screw 1426 can move freely through the aperture.The threaded portion of the screw 1426 is then inserted through thethreaded aperture in the second hinge portion 1424. The threadedaperture is preferably dimensioned such that the screw 1426 must berotated to pass through the threaded aperture. As the screw 1426 isrotated, the second hinge portion 1424 is drawn toward the first hingeportion 1422. When fully inserted, the unthreaded portion of the screw1426 generally is located at the unthreaded aperture of the first hingeportion 1422 and the threaded portion of the screw is engaged with thethreaded aperture of the second hinge portion 1424. In this position,the first hinge portion 1422 and second hinge portion 1424 arefrictionally engaged such that rotation of the first hinge portionrelative to the second hinge portion about the screw 1426 is resisted.In the embodiment in which one or both of the hinge portions 1422, 1424include textured surfaces, such as ridges, the engagement of thetextured surfaces may provide additional resistance against rotation. Anut may also be threaded onto any portion of the screw 1426 that extendsbeyond the aperture in the second hinge portion 1424 to help preventunintentional rotation of the screw 1426 when in the fully threaded,locked position.

The constrained hinge strut 103 b may also include an aperture 169 b.The aperture 169 b accepts a K-wire or other bone fastener that travelsinto the bone. The connection of the K-wire with the bone and theaperture 169 b of the constrained hinge strut 103 b lines the axis ofthe constrained hinge joint 168 b with the anatomic joint axis.

Now referring back to FIG. 12C, in one embodiment, constrained hingejoint 168 b is removably attached to non-rotating strut 134 b byconnection mechanism 199. Connection mechanism 199 may take any suitableform, such as a pin inserted through apertures, mating threads, snapfitting, press fitting, etc. In this embodiment, the particular joint,in this case a constrained hinge joint 168 b, may be removed andreplaced with a different type of joint, such as a universal hingejoint, polyaxial joint, or otherwise, depending on the particularrequirement or desire. This interchangeability allows, for example, aless complex process if a user desires to change the way in which aparticular strut is capable of moving.

Now referring to FIG. 14A, half-ring strut 103 c is illustrated.Half-ring strut 103 c is substantially similar to universal hinge strut103 a and constrained hinge strut 103 b, but includes both a universaljoint 162 c and a constrained joint 168 c. The half-ring strut 103 c maybe used to fix upper fixation ring 101 to half-ring 113.

Half-ring strut 103 c includes a length adjusting mechanism having athreaded strut 133 c and a non-rotating strut 134 c having an internalthread along at least a portion of a length thereof in which thethreaded strut 133 c engages. Half-ring strut 103 c may be connected tothe upper fixation plate 101 by means of an actuation unit 104 c and tothe half-ring 113 by means of a connecting element 104 c′. The actuationunit 104 c is preferably provided to actuate the length-adjusting strutin order to adjust its length.

The actuation unit 104 c may be substantially similar to the actuationunit 4 described above, including a ball and spring mechanism to provideauditory and/or tactile feedback. In the illustrated embodiment,half-ring strut 103 c includes a constrained 168 c near the connectingelement 104 c′ and a universal joint 162 c near the actuation unit 104c. The half-ring strut 103 c may also include a quick-release mechanism135 c.

A similar embodiment of half-ring strut 103 c is illustrated in FIGS.14B-E, which also includes a scale 136 c on the non-rotating strut 134c. The scale 136 c includes indicia along a slot, the slot allowing auser to visualize how far the threaded strut 133 c has advanced into thenon-rotating strut 134 c.

FIG. 14F illustrates an enlarged view of the connecting element 104 c′of the half-ring strut 103 c. In the illustrated embodiment, theconnecting element 104 c′ is bolt with external threading that mateswith internal threading in a portion of the constrained joint 168 c. Thebolt includes a portion with a diameter larger than the diameter of acorresponding aperture in a fixation element, such as the half-ring 113.This connection may be accomplished by other mechanisms, for exampleusing an internally threaded nut that threads onto the end of half-ringstrut 103 c. These mechanisms may apply with equal force to the otherstruts described herein.

In one embodiment of the fixation device, one universal hinge strut 103a fixes the top fixation plate 101 to the bottom fixation plate 102 at aposterior side of the device. Two constrained hinge joints 103 b fix thetop fixation plate 101 to the bottom fixation plate 102 at the medialand lateral sides of the device. A half-ring 113 is fixed at theanterior end of the bottom fixation plate 102, and a half-ring strut 103c fixes the half-ring 113 to an anterior portion of the top fixationplate 101. Each of the struts 103 a-c may be increased or decreased inlength as described above. The universal hinge strut 103 a allows fortop fixation ring 101 to move relative to the bottom fixation ring 102with rotation about three axes. The constrained hinge strut 103 b allowsfor the top fixation ring 101 to move relative to the bottom fixationring 102 with rotation about a single axis. The half-ring 113 isconstrained to rotation about one axis of rotation due to the hinges1320 connecting the half-ring to the bottom fixation ring 102. The axisabout which the half-ring rotates may be an axis that extends throughthe center of hinges 1320. The half-ring strut 103 c allows the topfixation ring 101 to be rotated about three axes with respect to thehalf-ring 113, due to the universal joint 168 c of the half-ring strut.This configuration allows the half-ring 113 to be assembled in multiplelocations and positions on the distal portion of the foot ring, thehalf-ring having a lockable hinge. The combination of the features aboveallows for increased control of the foot and ankle in order to properlyreturn it to an anatomic and functional position. The device also limitsand/or avoids the possibility of changing of motor struts duringtreatment. In addition, the half-ring 113 provides added strength to theframe itself, as described above, by bridging the two free ends of thebottom fixation ring 102.

Now referring to FIG. 15, another embodiment of a foot fixation frame isillustrated. The illustrated embodiment is a static frame, using thesame top and bottom fixation rings 101, 102 and half-ring strut 113 androcker 120 as described previously. This embodiment, however, includes adifferent configuration of struts. Specifically, four or more struts 103d connect the top fixation ring 101 to the bottom fixation ring 102. Byusing four or more struts 103 d, the rings 101 and 102 are overconstrained and do not change positions relative to one another. Assuch, the struts 103 d may be static struts. The struts 103 d may alsobe any of those described previously, but kept in a locked positionduring the deformity correction. For example, a strut capable ofpolyaxial movement may be used for struts 103 d. The strut may be angledinitially when fixing top fixation ring 101 to bottom fixation ring 102to provide for correct positioning, and then locked such that the strut103 d resists any additional repositioning.

The bottom fixation ring 102 may also include one or more footcompression modules 200, as illustrated in FIG. 15. Generally, the footcompression modules 200 are connected to the bottom fixation ring 102and half pins or wires (e.g. K-wires 114) extend from a firstcompression module 200, through (or into) the foot F, and are fixed onthe other side to the bottom fixation ring 102 or a second compressionmodule 200. These compression modules 200 allow for controlledmanipulation of the k-wires 114, and thus the bone fragments, during thedeformity correction process. Compression modules are more fullydescribed in U.S. Patent Publication No. 2011/0082458 and U.S. patentapplication Ser. No. 13/788,466 filed to Crozet et al., filed Mar. 7,2013, and titled “Dynamic External Fixator and Methods for Use.” Theentire content of each of these applications is hereby incorporated byreference herein. As discussed above, when tensioning the K-wires 114,using the compression modules 200 or otherwise, the projecting ends ofthe bottom fixation ring 102 tend to deform because of the applied forceand further because of the open shape of the bottom fixation ring. Theinclusion of the half-ring 113, connected in the same way as describedabove, resists deformation during tensioning of K-wires 114.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims. Forexamples, components of one embodiment described herein may be combinedwith components of another embodiment described herein without departingfrom the scope of the invention.

1. An external fixation frame for correcting a bone deformity,comprising: a top fixation ring; a bottom fixation ring; at least twoadjustable length struts coupling the top fixation ring to the bottomfixation ring; a half ring coupled between the top and bottom fixationrings; and a pair of hinges extending substantially perpendicularly froma top surface of the bottom fixation ring and hingedly coupling the halfring to the bottom fixation ring.
 2. The external fixation ring of claim1, wherein the half ring comprises a lateral end potion, a medial endportion, and an arcuate body portion connecting the lateral end portionto the medial end portion.
 3. The external fixation frame of claim 2,wherein the pair of hinges includes a first constrained hinge joint onthe medial end portion of the half ring and a second constrained hingejoint on the lateral end portion of the half ring.
 4. The externalfixation frame of claim 3, wherein the bottom fixation ring is U-shapedincluding a medial anterior projection, a lateral anterior projection,and a rounded posterior section connecting the medial anteriorprojection to the lateral anterior projection.
 5. The external fixationframe of claim 4, wherein the first constrained hinge joint couples themedial end portion of the half ring to the medial anterior projection ofthe bottom fixation ring and the second constrained hinge joint couplesthe lateral end portion of the half ring to the lateral anteriorprojection of the bottom fixation ring.
 6. The external fixation frameof claim 1, further comprising: an anterior adjustable length strutcoupling an anterior portion of the top fixation ring to the half ring,wherein the anterior adjustable length strut includes a distalconstrained hinge joint and a proximal universal hinge joint.
 7. Theexternal fixation frame of claim 6, wherein the distal constrained hingejoint of the anterior adjustable length strut is coupled to the arcuatebody portion of the half ring and the proximal universal hinge joint ofthe anterior adjustable length strut is coupled to the anterior portionof the top fixation ring.
 8. The external fixation frame of claim 1,wherein the two adjustable length struts are medial and lateraladjustable length struts, the medial adjustable length strut coupling amedial portion of the top fixation ring to a medial portion of thebottom fixation ring adjustable length strut and the lateral adjustablelength strut coupling a lateral portion of the top fixation ring to alateral portion of the bottom fixation ring.
 9. The external fixationframe of claim 8, wherein the medial and lateral adjustable lengthstruts each include a constrained hinge joint at one end thereof. 10.The external fixation frame of claim 8, further comprising a posterioradjustable length strut coupling a posterior portion of the top fixationring to a posterior portion of the bottom fixation ring, the posterioradjustable length strut including a universal joint at one end thereof.11. The external fixation frame of claim 1, wherein the half ringincludes an aperture with a diameter and the anterior adjustable lengthstrut includes a connecting element at a distal end thereof, theconnecting element including internal threading on the distal end of thestrut and an externally threaded bolt, a portion of the bolt having adiameter greater than the diameter of the half ring aperture.
 12. Theexternal fixation frame of claim 1, further comprising a rocker membercoupled to a bottom surface of the bottom fixation ring.
 13. Theexternal fixation frame of claim 12, wherein the rocker member comprisesa textured ground-contacting surface.
 14. The external fixation frame ofclaim 12, wherein the rocker member comprises a curved body portion withat least one connecting element projecting proximally from the curvedbody portion and configured to mate with an aperture in the bottomfixation ring in order to couple the rocker member to the bottomfixation ring.
 15. The external fixation frame of claim 14, wherein theat least one connecting element comprises: a main body portion extendingthrough an aperture in the curved body portion of the rocker member; anda distal flange extending distally of the main body portion, the distalflange configured to contact a corresponding shoulder portion of theaperture in the curved body portion.
 16. An external fixation frame forcorrecting a bone deformity, comprising: a top fixation ring; a bottomfixation ring having first and second elongate portions connected by anintermediate portion; at least three struts coupling the top fixationring to the bottom fixation ring; a half ring coupled between the topand bottom fixation rings and having first and second end portionsconnected by an arcuate portion; and a pair of hinges coupling the halfring to the bottom fixation ring, wherein the first end portion of thehalf ring is coupled to the first elongate portion of the bottomfixation ring and the second end portion of the half ring is coupled tothe second elongate portion of the bottom fixation ring.
 17. Theexternal fixation frame of claim 16, further comprising: at least onebone fastener having a first end operably coupled to the first free endof the bottom fixation ring and a second end operably coupled to thesecond free end of the bottom fixation ring, wherein the at least onebone fastener comprises a K-wire.
 18. The external fixation frame ofclaim 17, further comprising a first compression module coupled to thefirst elongate portion of the bottom fixation ring and a secondcompression module coupled to the second elongate portion of the bottomfixation ring.
 19. The external fixation frame of claim 18, the firstend of the bone fastener being coupled to the first compression moduleand the second end of the bone fastener being coupled to the secondcompression module.
 20. The external fixation frame of claim 16, whereinthe at least three struts coupling the top fixation ring to the bottomfixation ring include a medial, a lateral and an anterior adjustablelength strut, the anterior adjustable length strut coupling an anteriorportion of the top fixation ring to the half ring.
 21. The externalfixation frame of claim 20, wherein the medial adjustable length strutcouples a medial portion of the top fixation ring to a medial portion ofthe bottom fixation ring, and the lateral adjustable length strutcouples a lateral portion of the top fixation ring to a lateral portionof the bottom fixation ring.